Stewzer55

There is a great wealth of information on the '82 CFI here, so much so that I need help in finding the right direction to go with figuring out what I need to do to get this '82 running right so it may be enjoyed and driven as it should be.

1982 Corvette with 22K miles, it's had its fuel injectors replaced, new cap, rotor coil, plugs, fuel filter, air filters, TPI fuel pump and it still has a stumbling, surging idle, poor acceleration and is generally running poorly.

I understand that the fuel pressure regulator may need adjustment and have tried to get it adjusted the best I can without a fuel pressure gauge and without the proper tool to adjust it on the intake.

Any advice will be greatly appreciated.

hugie82

The fuel pressure regulator is sealed under a block off cap on the rear TB. did you remove the block off ?
I found most CFI vettes I've worked on have a huge vacuum leak under the plenum plate. So you need to install the felpro gasket under it.
Second, CFI vettes like a lot more timing advance than the manual calls for.
Doing those two things will usually get it running good!

Stewzer55

Thanks, I did read about the plenum gasket, yes, I did punch out the block-off on the rear tb, I think I might need to increase the pressure some more. It seems all the smog era cars seem to like more timing that than the manuals call for that I have found, it makes them run better but smoggier IIRC.

bebezote

i got scammed on an 82 vette that the supposed motor burnt 2 quarts of oil on the power tour.... junk....scammers will eventually pay one way or another...

GUSTO14

The cross shaft on the CFI throttle bodies have been notorious for wearing and resulting in vacumn leaks, even on relatively low mileage cars. Do a search on them and you may find the information helpful in diagnosing your problem.

Good luck... GUSTO

DUB

I HATE to write this...BUT GUSTO14 is correct...if the throttle shafts have play in them...you have a problem. OR the potential of a problem.

AS for 'guessing' on what you fuel pressure is pointless. YOU MUST use a fuel pressure gauge. And also hooking up a scanner would be advisable. You have to have the correct tools when working on this car. If not...you are fighting a loosing battle. This is FROM EXPERIENCE> I have everything from A-Z and including the manometer to balance the throttle bodies.

You have an issue with either a vacuum leak...coolant temp sensor and IAC's...or fuel pressure. The voltage value of your TPS is also a factor to some degree. You value in volts of your MAP sensor will let you know a lot if you hooked up a scanner.

Surging or 'hunting idle' ..especially when the computer has gone into 'CLOSED LOOP" is an indicator of low fuel pressure. High probability that that is what it is...but more can come into play here.

DUB

Lakeside49

From personal experience with my `82, there is a good chance - based on what you have said that you have already done - you have a vacuum leak. I did everything that you stated that you did - and, what you did was important, then there were two things that I believe fixed mine: 1. went through the entire vacuum system, particularly the headlight system, and snipped off 1/4" of hose from every connection to give it a fresher connection. Then, 2. I tightened the intake manifold bolts using a regular ratchet wrench. The idle slowed down and my seasoned (40 years) Corvette shop owner said that my crossfire runs like they did when they were new.

Dave

DUB

He can easily remove and cap the vacuum port on the intake and take the headlights and HVAC vacuum out of the equation by removing the hose at that port fitting.

If the engine idles fine when it is cold and then all of a sudden ...when it has gotten warmer...it all of a sudden starts to 'hunt' the idle and go up and down. I would be looking at your O2 sensor values and then if it is in CLOSED LOOP...I would bet ti will have something to do with your fuel pressure not being set high enough.

If you don't have one...you can find a Snap-On 'red brick' scanner for cheap. it will give you the data you need to know.

DUB

Lakeside49

Dub, you are an asset to this special Forum - thanks for all you do.
Dave

DUB

Dave,
I do what I can....anything that can save time and aggravation and still achieve a good end result.

'Spinning my wheels' in a repair is something that I can not afford due to doing this for a living...so I pass along 'things' that will give help people. If they choose to do it is up to them.

DUB

Lakeside49

Well - it sure is appreciated, sir.

Stewzer55

Thanks for your help, it surges when cold too and will die.
Does the engine have to be running to set fuel pressure?
Where can I get the FPR adjustment tool? DCS seems to no longer be selling anything.
The TB shafts don't seem to have any play in them.
The only OBD-1 scanner I have is a bent paper clip right now.
I would not put it past the headlight vacuum system to be leaking, I thought it was okay because the headlights come up just fine.
I know that the '74 parked next to it has new headlight vacuum lines and I'd prefer that it was converted to electric anyway (cam cam cam).

DUB

New vacuum lines does not mean that the system is sealed.

DUB

LastC3AZ

WTF ......... Why am I hearing this on here instead of a call from you directly .??????????? And how long have you had the car now ..... BS !!!!!!!!!!!